A rocket stove is an innovative clean and efficient cooking stove using small diameter wood fuel which is burned in simple high-temperature combustion chamber containing an insulated vertical chimney which ensures complete combustion prior to the flames reaching the cooking surface. The principles were described by Dr. Larry Winiarski from Aprovecho in 1982 and stoves based on this design won Ashden Awards in both 2005 and 2006. Interest in rocket stoves has led to the development of rocket mass heaters and other innovations.
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A rocket stove achieves efficient combustion of the fuel at a high temperature by ensuring that there is a good air draft into the fire, controlled use of fuel, complete combustion of volatiles, and efficient use of the resultant heat. It has been used for cooking purposes in many third-world locales (notably Rwandan refugee camps) as well as for space and water heating.
A rocket stove's main components are:
The fuel magazine can be horizontal where additional fuel will be added manually or vertically for automatic feeding of fuel. As the fuel burns within the combustion chamber convection draws new air into the combustion chamber from below ensuring that any smoke from smoldering wood near to the fire is also drawn into the fire and up the chimney. The chimney can be insulated to maximize the temperature and improve combustion, according to studies this will increase efficiency by up to two percent more.In a rocket mass heater the heat is passed into a suitable heat exchanger to ensure the efficient use of the generated heat.
For cooking purposes the design keeps the cooking vessel in contact with the fire over the largest possible surface area a pot skirt can be used to create a narrow channel which forces hot air and gas to flow along the bottom and sides of the cooking vessel. Optional baffles guide hot air and flame up the sides of the pot. For space heating purposes the heat is transferred to a heat store which can in some cases be part of the structure of the house itself. The exhaust gasses then pass out of the building via the chimney.
The design of stove means that it can operate on about half as much fuel as a traditional open fire and can use smaller diameter wood.If they are insulated and raised from the floor this reduces the danger of children burning themselves. Some more recent designs are self feeding using gravity to add fuel to the fire as required.
A precursor to the rocket stove was the argand lamp which was patented in 1780. This was a major development of the traditional oil lamp which introduced a glass chimney above the flame to increase air-flow. As well as being used for lighting, this design was also used for cooking and heating water due to its 'affording much the strongest heat without smoke'.[1]
Dr. Larry Winiarski, now Technical Director of Aprovecho, began developing the Rocket Stove in 1980 based on a VITA stove, designed by Sam Baldwin, using the systems developed by the Romans in hypocaust heating and cooking systems.[2] and invented the principles of the Rocket stove in 1982.[3] TWP and AHDESA were winners at the Ashden Awards for Sustainable Energy in 2005 in the 'Health and Welfare' category for their work in Honduras with the 'Justa Stove' which is based on principles of the rocket stove.[4] Aprovecho were winners of the Special Africa Award at the Ashden Awards in 2006 for their work with rocket stoves for institutional cooking in Lesotho, Malawi, Uganda, Mozambique, Tanzania and Zambia.[5]
The rocket stove was originally developed for cooking purposes where a relatively small amount of heat is required on a continuous basis which is applied to the bottom and sometimes also the sides of the cooking pot. Stoves can be constructed from brick, old tin cans, steel or be purchased.
Rocket Stoves are found more commonly in the third world countries where wood fuel sources are more scarce but it has been introduced in the United States in the recent years. Some of them are small for portability with insulation inside a double-walled design with a chamber for partial biomass gasification and additional mixing to increase BTUs and provide a cleaner, more complete burn. The advantage of these rocket stoves is the very little fuel they need, such as wood and dry weeds, to be able to cook a whole meal with it, keeping the air more clean with less hydrocarbons and carbon monoxide.
The rocket mass heater uses the rocket stove principle within a system designed to both heat air directly and also to transfer much of the heat from the flue gasses into a thermal energy storage, often made of cob.[6] Described in detail in 2006, these heaters are becoming popular in DIY builders, natural buildings and within permaculture systems.[7]
Rocket stoves can be used to heat water via a heat exchanger which transfers heat to a body of water in a nearby container.[8]
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